When a mechanical switch containing a metal contact is switched on or off, the contact may not be steadily switched on or off at once due to the elastic effect of the contact, but a series of bouncing (i.e., a series of switching on and off) occurs at the moment of switching on or off. The bouncing time may be more than 20 ms. Contact bouncing (or keypad bouncing, switch bouncing) may cause that one manual switching operation will be read by mistake for multiple times. This bouncing will cause a “double hit” response of a circuit in a less serious case, and will cause complete failure of circuit design in a severe case to cause various accidents. Therefore, the contact bouncing has to be eliminated in some applications. Method for eliminating the contact bouncing include a hardware method, a software method and other methods. The hardware method is to add a de-bouncing circuit, while the software method includes a delay method and a sampling method. These methods are introduced in the following literatures.    [1]. Li Hongyu, Huang Hesong and Ji Peifeng. Three Reliable Methods for Preventing Mechanical Bouncing [J], Electronic Component Application, 2004, 6(6), 53-55.    [1]. Zeng Yi, Xi Dashun and Li Xiangyang, Keypad Switch Bouncing and De-bouncing Method [J], Electronics World, 2005, (9), 55-56.    [2]. Fang Long, Xiao Xianbao and Li Wei. Study about Removing Keypad Mechanical Bouncing [J], Guangxi Journal of Light Industry, 2008, (1), 92, 105.
Patent document with an application No. 201110340157.5 “Keypad de-bouncing method, apparatus and keypad” and patent document with an application No. 200910058845.5 “Keypad de-bouncing method and system” disclose keypad de-bouncing through keypad information processing method and system. Both patent document with an application No. 201310004739.5 “Anti-bouncing circuit” and patent document with an application No. 201210555174.5 “Switch circuit capable of eliminating mechanical bouncing” de-bounce through an anti-bouncing circuit. Patent document with an application No. 200780034448.3 “Switch circuit and related de-bouncing method” conducts de-bouncing treatment on the output quantity of a switch through a sigma-delta modulator. American patent 7809867 “Keypad de-bouncing apparatus and method” and American patent application 20110004711 “Keypad de-bouncing apparatus and method” also eliminate keypad bouncing through circuit design. No matter the hardware method or the software method eliminates the influences of contact and keypad bouncing through circuit, circuit hardware or circuit software. According to the present invention, the contact bouncing will be fundamentally weakened or eliminated by plating a layer of tin alloy or lead alloy on a metal material of the contact, and the arc-ablation resistance or service life of the contact will be improved in the meanwhile.
The invention with an application patent number 201110193369.5 of the inventor provides a “Pitted-surface metal and rubber composite conductive particle” which is formed by adhering a metal surface layer to a rubber matrix or slitting after adhesion. The metal surface layer is a pitted surface and has concave pits or convex points or both the two; the concave pits or convex points are formed on an outer surface, or an inner surface of the metal surface layer, or both the outer surface and the inner surface; the depths of the concave pits are smaller than the thickness of the metal surface layer; and the heights of the convex points are no less than one tenth of the thickness of the metal surface layer. The metal surface layer is made of metal or alloy; gold, silver, copper, aluminum, nickel, chromium, rhodium, zinc, molybdenum, tin, cobalt, tungsten or ferrum and alloy thereof can be coated on the outer surface of the metal surface layer; the rubber matrix is made of silicone rubber or urethane rubber; an adhesion layer can be arranged between the metal surface layer and the rubber matrix; the adhesion layer is made of a heat vulcanization adhesive, a prime coat or a material identical to the rubber matrix. Aids such as a coupling agent can be coated on the inner surface of the metal surface layer. The metal surface layer of the invention has high strength and stable conductivity of electricity, the adhesion layer has high strength, and the rubber matrix has sufficient elasticity. However, the invention does not provide solutions for solving the bouncing problem and arc-ablation problem of the conductive particle. The invention does not provide a specific method about how to obtain one or more plated layers on the outer surface of the metal surface layer either, and does not explain how to selectively deposit a metal plated layer on the metal surface without depositing rubber.